1. Technical Field
The present invention relates to the technical field of cable driving devices for use in window regulators of automotive vehicles and so on.
2. Description of the Related Art
Generally, cable driving devices of this type, a power window equipped in a vehicle, for example, automatically open and close a window by feeding and winding up cables (wires) wound around a drum (reel) associated with a driving motor by the rotation of the drum to vertically move an actuator coupled to a window glass. Since such a cable driving device is constructed to accommodate in a casing, opposing a worm gear formed at a distal end of a motor shaft, a worm wheel meshed with the worm gear, and a damper mechanism for absorbing shock, and to have a drum wound with a cable and coupled to a protruding distal end of a driving shaft extending outwardly from the bottom of the casing, the cable driving device also requires a casing for accommodating the drum, resulting in a complicated structure having the casings formed both in front of and behind the cable driving device, and an axially extending configuration. In addition, since a power transmission path has a stroke extending in the axial direction, the cable driving device inevitably suffers from a large loss in transmission efficiency. Further, the cable driving device necessarily requires a large number of parts.
On the other hand, as shown in Japanese Unexamined Patent Publication (Kokai) No. Hei 1-182616, a casing (a housing, a gear case), opposing a worm gear formed on a motor shaft (armature shaft), is formed in the shape of a one-side-open closed cylinder, wherein a drum wound with the cables is disposed on the cylinder bottom side of a worm wheel meshed with the worm gear, while a damper for absorbing shock is disposed on the casing opening side of the worm wheel, the casing opening is closed by a cover, and the worm gear is meshed with the casing in which the drum is disposed, thereby accommodating all necessary parts within the single casing.
However, in such a cable driving device, a cable may protrude from the casing and therefore be exposed to water. In addition, since the casing is formed with draw-out openings for drawing the cables, it is difficult to prevent water from entering into the casing. If the entering water further flows into the worm wheel, the water may advance along the worm meshed with the worm wheel to wet a metal-made motor shaft of an electric motor, and to wet the damper interposed between the worm wheel and the cable drum. Then, this situation may cause failures and damage such as oxidization of the motor shaft, resulting in strange sound generated therefrom, deteriorated damper, and so on. It is therefore necessary to provide a water-proof structure for the casing, and smooth drainage for the water which has entered.
For this purpose, as shown in, for example, Japanese Unexamined Patent Publication (Kokai) No. Sho 56-97082 and Japanese Unexamined Utility Model Registration Publication (Kokai) No. Sho 59-35579, attempts have been made to prevent water from entering and reaching a worm wheel by dividing a casing into a section for accommodating a worm wheel and a section for accommodating a cable drum using a water-proof member. Such attempts, however, require partitioning members for water-tight dividing of each section. The former utilizes a rubber partitioning member having a seal lip formed along the outer periphery, while the latter utilizes a partitioning member having an O-ring fitted in the inner periphery. Thus, these attempts result in a problem of an increased number of parts and a complicated structure. In addition, as the cable driving device is driven, the seal lip slides in contact with the inner peripheral surface of the casing in the former structure, while the O-ring slides in contact with the outer periphery of the driving shaft, so that the sliding portions are rubbed to wear, thus giving rise to a problem of impaired durability and reduced efficiency due to the sliding resistance.
To address these drawbacks, as shown in Japanese Utility Model Registration Publication (Kokoku) No. Hei 5-7423, a casing formed with a groove communicating with a drain port (water discharge hole) on a peripheral wall thereof has been proposed to solve the foregoing problem.
However, the structure shown in the aforementioned Japanese Unexamined Patent Publication (Kokai) No. Hei 1-182616 involves assembling the drum with a pair of cables extending from the drum passing through the throughholes formed through the peripheral wall of the casing cylinder, thereby presenting a poor operability. Further, since the worm wheel, the drum and the damper are stacked in a three-layered structure, the resulting cable driving device is thicker in the axial direction, which prevents the resulting device from being compact in size and prevents the device from being incorporated into a thin door. Moreover, since this cable driving device includes the worm wheel which causes the damper and the drum to be spaced by a long distance, problems arise that members required for coupling them result in an increased number of parts, and that a loss in power transmission causes a lower efficiency. Here exist problems to be solved by the present invention.
On the other hand, the structure shown in the aforementioned Japanese Utility Model Registration Publication (Kokoku) No. Hei 5-7423 has an inner cylinder formed inside the peripheral wall of the casing in such a manner that the inner cylinder extends vertically from the bottom of the casing to define a space between the inner peripheral surface of the peripheral wall and the outer peripheral surface of the inner cylinder as a trough groove to guide entering water to the drain port. However, for accommodating a worm wheel meshed with a rotating worm in association with a driven motor on the bottom side of the casing, the inner cylinder must be constructed to surround the outer periphery of the worm wheel in order to protect the worm wheel from water, in which case the peripheral wall of the casing should be extended more outward to ensure a space for defining the trough groove, resulting in an inevitably larger diameter of the casing. However, a problem of hindering a reduction in size. Further, since the drain port is simply formed at a comer of the bottom of the casing and the peripheral wall, sufficient care should be taken against water entering through the drain port from the outside which may further reach into the casing. Thus, the shown structure cannot be employed as it is, and here exist problems to be solved by the present invention.
To solve the problems, the present invention provides a cable driving device comprising a bottomed and cylindrical-shaped casing having an opening at one side and facing a worm gear which is rotatable in association with a driven motor, a cover for closing the opening of the casing, a worm wheel incorporated in the casing and meshed with the worm gear, a drum wound with cables drawn out from the casing, and a damper for transmitting the driving force of the motor from the worm wheel to the drum in a damped state (shock-absorbed state), wherein the damper and the drum are formed respectively with damper bodies and drum tongues fitted into cavities formed through the worm wheel in opposition to each other in a rotating direction about an axis, the casing comprises draw-out guides protrusively formed in a groove shape with its casing opening side opened for drawing out the cables extending from the drum, and the cover is protrusively formed with guide closures for closing the draw-out guides. With such an arrangement, the cables can be drawn out from the casing by inserting the cables into the groove-shaped draw-out guides with the cables being wound around the drum, thereby improving the assembling operability and also enabling automated assembly.
By the thus constructing the cable driving device, despite a damper-based mechanism which does not require a pair of coil-type springs, a power transmission mechanism comprising a damping function implemented by the worm wheel, the damper and the drum can be accommodated within the thickness of the worm wheel to reduce the thickness of the overall casing. Also, the worm wheel, the damper and the drum are disposed in close proximity to one another to reduce the number of parts. Further, since the power transmission having the damping function can be performed within the thickness of the worm wheel, highly efficient power transmission is accomplished.
In the cable driving device, the damper bodies are fitted into the cavities formed through the worm wheel from the casing opening side, and the damper tongues are fitted into the cavities from the casing opening side so as to be opposite to the fitted damper bodies in the rotating direction about the axis, in which case, the worm wheel, the damper and the drum can be sequentially assembled into the casing from the casing opening side, thereby simplifying the assembling operations.
In the foregoing structure, the cable driving device can be characterized in that the cover is formed with a fitting portion for loosely fitting the drum from an end portion on a cable winding side, in which case the drum wound with the cables can be placed closer to the opening of the casing, the depth of the grooves of the draw-out guides can be reduced, the closing of the draw-out guides with the cover can improve the water-proof capability with a reduced seal margin, and the depth of the casing can be made as thin as possible, thereby reducing the size of the device.
Further, in the foregoing structure, the cable driving device can be characterized in that the casing includes a supporting shaft protruded from the bottom toward the opening side, the worm wheel and the drum are rotatably supported on the supporting shaft, and the cover is formed with a shaft support for receiving and supporting a distal end of the supporting shaft, in which case the worm wheel and the drum are supported by the supporting shaft which has both ends supported by the casing and the cover, thereby supporting the worm wheel and drum securely.
Furthermore, in the foregoing structure, the cable driving device can be characterized in that the damper is accommodated within the thickness of the worm wheel, and the drum is disposed adjacent to the casing opening side of the worm wheel with the damper accommodated therein, in which case a power transmission path from the worm wheel to the drum through the damper is made shorter in the axial direction, thereby further improving the power transmission efficiency.
Also, a casing peripheral wall is formed with draw-out guides for drawing out the cables extending from the drums, and a drain port for discharging water in the casing, and the casing includes a conduit trough assembled therein on the casing opening side for guiding water having entered therein from the draw-out guide to the drain port.
In this way, water can be prevented from entering into the worm wheel without increasing the size of the casing.
In the cable driving device, the conduit trough of the present invention can be integrally formed with connector pieces which are fitted into guide holes of the draw-out guides.
Further, in the cable driving device, the conduit trough of the present invention can have a U-shape in cross-section which is open on the same side as the casing opening, and the bottom of the conduit trough can be formed to extend from the position of a casing peripheral wall to a position at which the conduit trough overlaps with the worm wheel on the casing opening side.
The conduit trough of the present invention can have the bottom formed in the shape of ring opposing the outer periphery of the worm wheel.
Also, in the cable driving device, the cable drum is formed with a collar protruding outwardly in a radial direction from the edge opposite to the worm wheel for guiding water attached to the cable drum toward the drain port to prevent the water from entering into the worm wheel.
In this way, the water having entered into the cable drum side can be prevented from further entering into the worm wheel.
Furthermore, the casing peripheral wall is formed with draw-out guides for drawing out the cables to the outside, and a drain port for discharging water in the casing to the outside, the worm wheel is formed with a protrusion around the outer periphery thereof on the cable drum side, wherein the protrusion is formed to oppose the outer periphery of the cable drum, and the protrusion has an inclined inner peripheral surface which has a larger diameter toward the distal end of the protrusion.
In this way, water having entered into the cable drum can be prevented from further entering into the worm wheel.
In the cable driving device, the protrusion of the present invention can be formed with a guide protrusion at a distal end thereof, protruding outwardly in a radial direction.
Further, in the cable driving device, the peripheral wall of the casing of the present invention can be formed with a rib protruding inwardly in the radial direction to oppose the guide protrusion on the bottom side of the casing.
Also, in the cable driving device, the draw-out guides of the present invention can include water-proof caps inserted into distal ends thereof.
Further, in the cable driving device, the drain port can be formed through the casing, and include a lower side extending to the bottom of the casing in a state in which the casing opening side is closed by the cover, and an upper side continuous from the bottom of the casing and can be set at a length overlapping with the lower side. Moreover, in this case, the upper side comprises a short casing peripheral wall which extends along the edge of the casing peripheral wall on the cover side not to a position at which the upper side is closed by the cover, but to a position at which the upper side overlaps with the lower side.